fix(CssManager): Make CssManager a singleton and export the shared instance via getSingleton; update tests and dependencies

readme.hints.md

@@ -1 +1,15 @@
- 
+# Project Hints
+
+## CssManager Singleton Pattern
+
+**Location:** `ts/classes.cssmanager.ts`
+
+The `CssManager` class uses a singleton pattern:
+- **Static method:** `CssManager.getSingleton()` - Returns the singleton instance
+- **Exported instance:** `cssManager` (from `ts/index.ts`) - Uses `getSingleton()` internally
+
+Both access patterns are supported for backward compatibility:
+- `cssManager.method()` - Legacy pattern (still works)
+- `CssManager.getSingleton().method()` - Preferred pattern
+
+The singleton ensures only one instance manages CSS variables and theme changes throughout the application.